On-and-off floods formed Mars valleys

Floods that created distinctive features of Mars were not of a catastrophic sort, scientists claim.

An­cient net­works of val­leys on Mars were carved by re­cur­rent floods over a long per­i­od when the cli­mate may have been much like that of some ar­id or semiar­id re­gions on Earth, a new study sug­gests.

The re­sults don’t sup­port an al­ter­na­tive the­o­ry that the val­leys were carved by cat­a­stroph­ic flood­ing over a shorter time, the re­search­ers said.

Of­ten cit­ed as ev­i­dence that Mars once had a warm en­vi­ron­ment with liq­uid wa­ter on the sur­face, val­ley net­works are dis­tinc­tive fea­tures of the Mar­tian land­scape. In the new stu­dy, sci­en­tists used com­put­er mod­els to sim­u­late the pro­cesses that formed these fea­tures.

“Our re­sults ar­gue for liq­uid wa­ter be­ing sta­ble at the sur­face of Mars for pro­longed per­i­ods,” said Charles Barn­hart, a grad­u­ate stu­dent in Earth and plan­e­tary sci­ences at the Uni­ver­s­ity of Cal­i­for­nia, San­ta Cruz.

Barn­hart con­ducted the study as a Grad­u­ate Stu­dent Re­search Pro­gram schol­ar at NASA Ames Re­search Cen­ter, work­ing with plan­e­tary sci­ent­ist Jef­frey Moore at the agen­cy and Al­an How­ard of the Uni­ver­s­ity of Vir­gin­ia.

A pa­per de­scrib­ing their find­ings has been ac­cept­ed for pub­lica­t­ion in the Jour­nal of Geo­phys­i­cal Re­search—Planets.

“For sev­er­al dec­ades, sci­en­tists worked to de­ter­mine wheth­er or not there had ev­er been pre­cipita­t­ion on Mars. Only in the last 10 years has NASA ac­quired high-res­o­lu­tion top­o­graph­ic da­ta that cinched the case for mas­sive an­cient ero­sion from pre­cipita­t­ion and runof­f,” Moore said.



Source:http://www.world-science.net/othernews/080908_mars-valleys